Tubeless vertical form, fill and seal packaging machine with improved feed means

Abstract

A tubeless vertical form, fill and seal packaging machine has a tube former for receiving flexible packaging material in thin flat strip form and juxtaposing opposite longitudinal edge portions thereof in parallel vertically extending relationship to provide a depending tube open at the top. Side and end sealers respectively seal vertical longitudinal edge portions and provide vertically spaced horizontally extending end seals across the tube. A product dispenser discharges measured quantities of product into the tube interior through its open upper end. Improved tube feed means comprises first and second pairs of vertically spaced rolls respectively on opposite external sides of the tube of packaging material and first and second tube feeding belts respectively trained over said pairs of rolls. Inner runs of the belts engage the tube and have vertically extending imperforate marginal portions and a perforate intermediate portion. Vacuum generating means communicate with the intermediate perforate portions to cause the belts to grip the tube and tube guide and belt back-up means within the tube prevent lateral vacuum loss and provide for frictional tube feeding action. In one form, the back-up means comprise depending cantilevered thin flat members which provide frictional feeding action throughout the width of the belts. In a second form, first and second pairs of back-up members provide frictional feeding action only at the imperforate marginal belt portions. The rolls and belts are adjustable horizontally for varying frictional tube feeding action.

We claim: 
     
       1. A tubeless vertical form, fill and seal packaging machine comprising a source of flexible packaging material in the form of an elongated thin flat strip of material of uniform width comprising successive flat package blanks as integral longitudinally contiguous sections thereof, a tube former adapted to receive said strip material and to progressively form the same to a depending and upwardly open tubular configuration, opposite longitudinal edge portions of the material being progressively juxtaposed by said former so as to extend vertically in parallel relationship for side sealing, product dispensing means above said former and operable for the gravity discharge of measured quantities of product, vertically open tubular product guide means beneath said product dispensing means for receiving said measured quantities of product and for directing the same downwardly to the interior of the tube of packaging material through its said upwardly open end, said means extending vertically within said tube former in radially spaced relationship therewith and within the tube of packaging material formed therein, side and end sealing means disposed beneath said tube former and guide means respectively for sealing said vertically extending longitudinal edge portions of the tube and for providing successive longitudinally spaced horizontal end seals across the tube, first and second pairs of vertically spaced rolls respectively on opposite external sides of said tube of packaging material beneath said product guide mean, first and second tube feeding belts respectively trained over said first and second pairs of rolls, each belt having a vertically extending inner run engageable with the external surface of the tube of packaging material, and opposite vertically extending marginal portions of each belt being imperforate and an intermediate portion thereof perforate, vacuum generating means communicating with at least said intermediate perforate portions of each of said belts along their said inner runs to cause the belts to grip the tube of packaging material with the inner belt runs in engagement therewith, tube guide and belt back-up means disposed within the tube of packaging material in engagement with its internal surface and extending vertically opposite at least each imperforate marginal portion of each belt inner run whereby to prevent lateral vacuum loss and to provide for frictional tube feeding action with the inner belt runs externally engaging the tube, and means for driving at least one roll in each of said first and second pairs of rolls to cause said inner belt runs to travel downwardly in unison and thereby to effect combined vacuum-friction tube feeding action positively drawing the tube of material downwardly through the former and successively presenting said integral package blanks therebeneath in tubular form for filling, sealing and package formation. 
     
     
       2. A tubeless vertical form, fill and seal packaging machine as set forth in claim 1 wherein said first and second pairs of tube feeding rolls and their belts are arranged on opposite external sides of said tube of packaging material with the longitudinal edge portions of the tube displaced approximately 90° from each said pairs of rolls and belts, and wherein said side sealing means is arranged therebetween and adjacent said tube edge portions so as to engage and seal the same, the position and vertical dimension of said sealing means being such that its lower end does not extend substantially below said rolls and belts thus permitting location of said end sealing means closely therebeneath and minimizing the vertical distance through which the quantities of product must fall. 
     
     
       3. A tubeless vertical form fill and seal packaging machine as set forth in claim 2 wherein said side sealing means is adapted to engage and to seal together said longitudinal tube edges in transit and as the tube of material is drawn downwardly through the former by said tube feeding rolls and belts. 
     
     
       4. A tubeless vertical form, fill and seal packaging machine as set forth in claim 3 wherein said side sealing means is maintained in external pressure engagement with said longitudinal tube edge portions, and wherein a sealing back-up member is disposed within said tube of packaging material and extends vertically adjacent and engages internally said longitudinal edges whereby to react the force of said sealing means. 
     
     
       5. A tubeless vertical form, fill and seal packaging machine as set forth in claim 4 wherein said tube guide and belt back-up means and said sealing back-up member are each of minimal cross section viewed vertically so as not to interfere with free product fall within the tube of packaging material. 
     
     
       6. A tubeless vertical form, fill and seal packaging machine as set forth in claim 5 wherein said tube guide and belt back-up means and said sealing back-up member are each provided with a low friction surface material for free sliding engagement with the internal surface of the tube of packaging material. 
     
     
       7. A tubeless vertical form, fill and seal packaging machine as set forth in claim 5 wherein said end sealing means comprises a pair of opposing sealing jaws beneath said tube feeding rolls and belts and movable horizontally in unison toward and away from said tube of packaging material respectively to engage and end seal the tube and to free the tube. 
     
     
       8. A tubeless vertical form, fill and seal packaging machine as set forth in claim 7 wherein said end sealing jaws are adapted for operation independently of but in timed relationship with said tube feeding belts whereby to form packages of varying length from said tube of packaging material. 
     
     
       9. A tubeless vertical form, fill and seal packaging machine as set forth in claim 1 wherein said tube guide and belt back-up means comprises first and second elongated vertically extending thin flat members respectively disposed internally of the tube of packaging material in opposing relationship with said first and second tube feeding belts, each of said back-up members having a width approximately equal to the width of its associated belt so as to provide frictional feeding action throughout the width of each belt. 
     
     
       10. A tubeless vertical form, fill and seal packaging machine as set forth in claim 9 wherein said back-up members are secured at upper end portions to said tubular product guide means and depend therefrom in cantilever relationship within the tube of packaging material, said members having at least minimal spring characteristics so as to resiliently back up and react the force of their respective tube feeding belts. 
     
     
       11. A tubeless vertical form, fill and seal packaging machine as set forth in claim 10 wherein said tube guide and belt back-up members have a low friction surface for free sliding engagement with the internal surface of the tube of packaging material, and wherein said tube feeding belts each have a high friction surface for gripping engagement with the external tube surface. 
     
     
       12. A tubeless vertical form, fill and seal packaging machine as set forth in claim 11 wherein said back-up member surfaces are of a fluorocarbon polymer, and wherein said belt surfaces are of a rubber-like material. 
     
     
       13. A tubeless vertical form, fill and seal packaging machine as set forth in claim 1 wherein said tube guide and back-up means comprises first and second pairs of elongated vertically extending flat faced members disposed internally of the tube of packaging material respectively in opposing relationship with said first and second tube feed belts, the back-up members of each pair being spaced apart horizontally so that their said flat faces respectively oppose the opposite imperforate marginal portions of the associated feed belt, and the width of said flat faces being approximately equal to the width of said marginal belt portions for frictional feeding action throughout the width of said marginal portions. 
     
     
       14. A tubeless vertical form, fill and seal packaging machine as set forth in claim 3 wherein said back-up members are secured at upper end portions to said tubular product guide means and depend therefrom in cantilever relationship within the tube of packaging material, said members having at least minimal spring characteristics so as to resiliently back-up said tube feeding belts. 
     
     
       15. A tubeless vertical form, fill and seal packaging machine as set forth in claim 14 wherein said tube guide and belt back-up members have a low friction surface for free sliding engagement with the internal surface of the tube of packaging material, and wherein said tube feeding belts each have a high friction surface for gripping engagement with the external tube surface. 
     
     
       16. A tubeless vertical form, fill and seal packaging machine as set forth in claim 15 wherein said back-up member surfaces are of a fluorocarbon polymer, and wherein said belt surfaces are of a rubber-like material. 
     
     
       17. A tubeless vertical form, fill and seal packaging machine as set forth in claim 1 wherein each of said imperforate marginal portions of each feed belt comprises at least 10% of total belt width. 
     
     
       18. A tubeless vertical form, fill and seal packaging machine as set forth in claim 17 wherein each of said imperforate marginal portions of each feed belt comprises approximately 20 to 25% of total belt width. 
     
     
       19. A tubeless vertical form, fill and seal packaging machine as set forth in claim 17 wherein said perforate portion of each feed belt has open vacuum area in the range of 20 to 60% of total area of the perforate portion. 
     
     
       20. A tubeless vertical form, fill and seal packaging machine as set forth in claim 1 wherein said tube feed belts and support rolls are mounted for horizontal adjustment toward and away from the tube of packaging material for varying pressure exerted by the belts on the material and reacted by the associated back-up means and for thereby adjusting frictional tube feed action. 
     
     
       21. A tubeless vertical form, fill and seal packaging machine as set forth in claim 20 wherein first and second support means are provided respectively for said first and second pairs of feed rolls and belts and are interconnected by elongated screw means having oppositely threaded portions for horizontal adjustment in unison and in opposite directions for the support means and their roll and belt assemblies on manual manipulation of the screw means.